I didn't actually look up the phrase in english to see what it originally meant. My interpretation of it (and how I applied it in the document I was working on) was that this person work hard to save a little bit of money in some areas (a "penny-pincher" to use another idiom), and then wasted a whole lot of money on something that he/she didn't need, or that wasn't worth such an exorbitant amount.

All of your ideas and suggestions have made me think about all the nuances the idiom could have.

I this person work hard to save a little bit of money in some areas (a "penny-pincher" to use another idiom), and then wasted a whole lot of money on something that he/she didn't need, or that wasn't worth such an exorbitant amount. .